Question 842163
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Hi,
When Lily was 3 months old, she weighed 10 pounds. 
She is gaining about 3/4 of a pound each month. 
How much should she weigh after 18 months?
Let x represent the number of months:
 weight = (3/4)(x-3) + 10lb
 weight at 18mo  = (3/4)(18-3) + 10lb = 21.25lb   0r 21 <sup>1</sup>&frasl;<sub>4</sub> lb